Thanks for all the suggestions...looks like there are two basic approaches...use an outboard flash handle with a remote shutter switch...or...the vertical grip...also sounds like a trip to my local camera shop {about 60 miles away...they seem to be harder to find these days

} is in order.
This is a tough situation. I believe a tripod and remote release will help him a lot. Aren't there specialty businesses that sell assistive devices for disabled people?
There used to be, but it was years ago. I did some left handed and pistol grip cameras. Opened up the camera, added connectors in parallel with existing buttons and dials, and came out to a connector. Then made left hand grips or pistol grips with additional buttons and quadrature-dials (that's the kind of mechanism that makes the command dials work).
But the outfit I did that for is gone, and I don't know enough about the business end of that kind of operation to manage it. They were a non-profit and used to get most of the engineering funded through US state and federal government agencies, charitable foundations, insurance companies, and employers. Then bid jobs to a number of engineers and techs who concocted the modifications. I did cameras and woodwind instruments.
These days, with all the cameras having USB based interfaces, it should be a snap to build a universal pistol grip or left hand grip that just plugs into the USB port and runs camera functions by button, dial, and voice controls. I got as far as a PC based prototype and the basic design for the grip (gum-stick computer, embedded Linux, Mississippi state voice recognizer) before running out of steam.
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Rahon Klavanian 1912-2008.
Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.
Ciao! Joseph
http://www.swissarmyfork.com